From 9ebf333e48c57a72c75e4be4f5f0e991bc2635a6 Mon Sep 17 00:00:00 2001
From: Davide Oddone <davide@oddone.dev>
Date: Fri, 1 Dec 2023 21:55:41 +0100
Subject: [PATCH] Second part of the first event

---
 20231201/trebuchet.go | 83 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 79 insertions(+), 4 deletions(-)

diff --git a/20231201/trebuchet.go b/20231201/trebuchet.go
index caf0def..1b03d51 100644
--- a/20231201/trebuchet.go
+++ b/20231201/trebuchet.go
@@ -2,11 +2,19 @@ package main
 
 import (
     "fmt"
+    "strings"
     "bufio"
     "os"
     "strconv"
 )
 
+type Number int
+
+var numbers = []string {
+   "one", "two", "three", "four", "five",
+   "six", "seven", "eight", "nine",
+}
+
 func check(e error) {
     if e != nil {
         panic(e)
@@ -18,7 +26,8 @@ func ExtractCalibration(s string) string {
 	firstDigit := 0
 	lastDigit := 0
 	index := 0
-	
+
+	// Start from the beginning of the string, stop when you find a number
     for i := 0; i < len(s); i++ {
        if num, err := strconv.Atoi(string(s[i])); err == nil {
            firstDigit = num
@@ -27,6 +36,7 @@ func ExtractCalibration(s string) string {
        }
     }
 
+	// Start from the end of the string, stop when you find a number
     for j := len(s) - 1; j >= index; j-- {
        if num, err := strconv.Atoi(string(s[j])); err == nil {
            lastDigit = num
@@ -38,11 +48,73 @@ func ExtractCalibration(s string) string {
     return fmt.Sprint(firstDigit) + fmt.Sprint(lastDigit)
 }
 
+func SearchFirstIndex(s string) int {
+    // len(s) will always be bigger than the first index where you
+    // can have a substring match
+    index, number := len(s),0
+    // from 1 to 9, save the smallest index and the number
+    for i := 1; i < 10; i++ {
+        tempIndex := strings.Index(s, fmt.Sprint(i))
+        if tempIndex < index && tempIndex != -1 {
+            index = tempIndex
+            number = i
+        }
+
+    }
+    // again for strings, from [0] "one" to [8] "nine"
+    // save the smallest index, if smaller than the previous
+    for i := 0; i < 9; i++ {
+        tempIndex := strings.Index(s, numbers[i])
+        if tempIndex < index && tempIndex != -1 {
+            index = tempIndex
+            number = i + 1
+        }
+    }
+
+    return number
+}
+
+func SearchLastIndex(s string) int {
+    // -1 will always be smaller than the last index where you
+    // can have a substring match
+    index, number := -1,0
+    for i := 1; i < 10; i++ {
+        tempIndex := strings.LastIndex(s, fmt.Sprint(i))
+        if tempIndex > index && tempIndex != -1 {
+            index = tempIndex
+            number = i
+        }
+
+    }
+    for i := 0; i < 9; i++ {
+        tempIndex := strings.LastIndex(s, numbers[i])
+        if tempIndex > index && tempIndex != -1 {
+            index = tempIndex
+            number = i + 1
+        }
+    }
+
+    return number
+}
+
+func CombineIndexes(s string) int {
+    firstNumber := SearchFirstIndex(s)
+    secondNumber := SearchLastIndex(s)
+
+    combinedString := fmt.Sprint(firstNumber) + fmt.Sprint(secondNumber)
+
+    combinedNumber, err := strconv.Atoi(combinedString)
+    _ = err
+
+    return combinedNumber    
+}
+
 func main() {
 	file, err := os.Open("input")
 	check(err)
 
-	var total int = 0
+	var firstTotal int = 0
+	var secondTotal int = 0
 
 	scanner := bufio.NewScanner(file)
 
@@ -51,7 +123,10 @@ func main() {
     	calibration := ExtractCalibration(line)
     	num, err := strconv.Atoi(calibration)
     	_ = err
-    	total += num
+    	firstTotal += num
+    	secondTotal += CombineIndexes(line) 
 	}
-	fmt.Println(total) 
+	fmt.Printf("Calibration value, first method: %d\n", firstTotal)
+	fmt.Printf("Calibration value, second method: %d\n", secondTotal) 
+	
 }